1. Field of the Invention
The present invention relates to a power semiconductor device provided with a drive circuit that drives a totem-pole connected high side switching element and low side switching element, and more particularly, to a power semiconductor device capable of sufficiently charging a bootstrap capacitor, and simplifying and downsizing the circuit.
2. Background Art
A high side drive circuit that drives a high side switching element requires a drive voltage higher than a main power supply. It is therefore a known practice that the drive voltage is obtained by charging the bootstrap capacitor from a low side drive power supply. However, when the high side switching element is ON, a potential at one end of the bootstrap capacitor increases and the other end of the bootstrap capacitor cannot be charged. Therefore, there is a problem that the bootstrap capacitor cannot be sufficiently charged if the high side switching element keeps ON.
To solve this problem, a power semiconductor device provided with a refresh circuit for a bootstrap capacitor is proposed (e.g., see FIG. 2 of National Publication of International Patent Application No. 2007-520190). The refresh circuit secures a charge channel by selecting a switch SW1 or SW2 and thereby setting a potential at one end of the bootstrap capacitor to GND irrespective of the ON/OFF state of the high side switching element.